If X =

I did this

I used the law of indices, is it right to apply this for matrices?

Please help me, I am not sure if I did it right here!

Thank you!

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- Jan 18th 2013, 08:25 PMTutuMatrices proof
If X =

I did this

I used the law of indices, is it right to apply this for matrices?

Please help me, I am not sure if I did it right here!

Thank you! - Jan 18th 2013, 08:55 PMchiroRe: Matrices proof
Hey Tutu.

Hint: Group the P*P^(-1) = I (I is identity matrix) together to get a lot of cancellation and then use A^3 = I to get your final result. - Jan 21st 2013, 04:53 AMTutuRe: Matrices proof
Thank you!

I thought I could not change the order within the multiplication, but so is it that I can do it in thie case? Why?

Is it

X^3 = (P^(-1)PA)(P^(-1)PA)(P^(-1)PA)

= P^(-3) (PA)^3

= I

Wait, I did this using laws of indices again, can you please explain how to do it, I'm afraid I do not understand..

Thank you ever so much! - Jan 21st 2013, 07:08 AMDevenoRe: Matrices proof
your proof is incorrect.

NOT .

and since ,

.

no "switching around of order" is required. - Jan 21st 2013, 07:56 AMTutuRe: Matrices proof
Thank you!

Does that mean that in matrices, PP^(-1) = P? I thought it equalled to I - Jan 21st 2013, 07:57 AMTutuRe: Matrices proof
Sorry, ignore the previous post. I get it now!